在制动电阻选型过程中需要考虑的两大主要因素是功率和阻值,而对于温度的考量,在现行的国家标准中,并没有关于制动电阻温度的规定,而且现行的《电阻器基本技术条件》中关于电阻器极限温升的规定也只从电阻器的运行状况和人身安全角度考虑。
但是在制动系统中,除了要考虑电阻的运行情况外,还要从整个制动系统来衡量,比如在电梯系统中如果机房温度过高,会对控制柜的变频器等各种电子设备的散热产生影响。我们都知道,制动电阻主要是将再生电能转化为热能散发到空气中,直接影响的是整个制动系统的工作环境温度。
因此在选型时需要综合考虑电阻的使用环境等再确定功率和阻值,并且在安装操作中还需要注意以下问题:
1、避免将制动电阻和变频器安装的太靠近。
2、必须保证制动电阻有足够的的散热空间,必要时安装散热装置。
3、电阻的接头处必须安装稳固,避免电缆因长时间高温受损。
4、连接电缆长度不宜过长,避免斩波干扰。
In the selection process of brake resistance, two main factors need to be considered are power and resistance value. For the consideration of temperature, there is no stipulation on the temperature of brake resistance in the current national standard. Moreover, the stipulation on the limit temperature rise of resistor in the current Basic Technical Conditions of Resistors only considers the operation condition and personal safety of resistor.
But in the braking system, besides considering the operation of resistance, it also needs to be measured from the whole braking system. For example, if the room temperature is too high in the elevator system, it will have an impact on the heat dissipation of various electronic equipment such as the frequency converter of the control cabinet. As we all know, brake resistance mainly converts regenerated electric energy into heat energy and emits it into air, which directly affects the working environment temperature of the whole brake system.
Therefore, when choosing brake resistance, we need to consider the use environment of resistance comprehensively to determine the power and resistance value. In addition, we need to pay attention to the following problems in installation operation:
1. Avoid installing brake resistance and frequency converter too close.
2. It is necessary to ensure that the brake resistance has enough heat dissipation space and install heat dissipation devices when necessary.
3. The joint of resistance must be installed firmly to avoid cable damage due to long time high temperature.
4. The length of connecting cable should not be too long to avoid chopper interference.